1. Field of the Invention
The present invention relates to a pitched tile roofing system, and particularly to a system for insulating the pitched tile roof and attaching roofing components, and a method for installing the system.
2. Description of the Related Art
There are two basic types of roofs: flat and pitched. Pitched roofs come in a few basic styles, all of which are relevant to the present invention. A duo-pitched roof has two sloping sides joined along the top with end vertical walls called a gable end. This is probably the most common form of pitched roof. If the end of the roof is also sloping it is termed hipped. If two sections of roof meet at an angle, such as a right angle, the junction between the two roof sections is termed a valley.
Various roof components are used as roof coverings on pitched roof decks. One example of roof component is a roof tile. Roof tiles are extremely durable and provide significant aesthetic and decorative effects to the structures to which they are applied. Roof components or coverings as described herein may be made of cementitious materials and also brick, stone, clay, plastic, wood, metal, rubber or bituminous materials.
A typical pitched roofing system includes sheets of wood, typically plywood or decking material, nailed to the truss rafters to form a pitched roof deck. Other pitched roof decks may be made with materials such as steel or concrete. Typically, the pitched roof deck is overlaid with a roof substrate made of a waterproofing material. Typically, the waterproofing material forming the roof substrate is a roll goods membrane or underlayment comprising one or more plies of asphaltic or modified bitumen impregnated felt attached to the pitched roof deck. The felt is typically attached to the pitched roof deck by nails and/or adhesive. Felt is generally made of wood pulp and rag or of asbestos, polyester or glass fibers. Self-adhering membranes, commonly referred to as “peel and stick,” may also be used. These membranes are generally modified bitumen impregnated fiberglass or polyester fibers. Some pitched roof systems having steel or concrete decks do not require the use of a waterproof membrane or coating.
Roof components are primarily secured to the pitched roof deck with mechanical fasteners. Nails are the primary mechanical fasteners for securing roof components to a wood deck. Typically, tile roof components are secured with nails, inserted through holes in the tile roof component, driven into and through the roof substrate and wood deck. Mortar is sometimes used in conjunction with nails to provide holding force of the tile roof component to the roof deck. In either case, it is undesirable to drive numerous holes through the roof substrate and wood deck since these nail holes provide a potential leak path in the pitched roofing system. High wind loading conditions also affect the roof components secured with nails. In areas near salt water the effectiveness of nails is diminished over time due to corrosion of the nails. Additionally, nails get loose over a period of time. Some decks, such as concrete or steel decks, cannot be nailed into. Non-nailable decks (concrete, steel, etc.) use a wire tie or other cumbersome and expensive system to fasten the roof components to the pitched roof deck.
As stated above, mortar or similar binders are often used as a secondary fastener between tile roof components and the roof substrate. Using mortar is a slow procedure and labor intensive as the mortar must first be prepared, typically at ground level, in buckets which must then be raised to the pitched roof deck, and then the mortar is applied to the roof substrate. The mortar adds unnecessary weight to the roofing system. The set-up time of the mortar increases the time required to form the bond between the tile roof component and the roof substrate. The installed tile roof components should not be disturbed until the mortar has set-up as movement of the tile roof component affects the bond. Furthermore, the strength of the completed bond between the tile roof component and the roof substrate can be unsatisfactory. Typically, an approximate 60-pound tensile load applied transversely to the tile roof component will break the mortar bond between the tile roof component and the roof substrate. During high wind loading conditions, such as that experienced during a hurricane or a tornado, the tile roof components frequently release from the roof structure and become life threatening, flying projectiles. During such events, the tile roof components are widely strewn about and scattered throughout the area. The flying tile roof components result in additional danger during these devastating events and further increase the tremendous burden of clean up after these catastrophic events.
Assignee's U.S. Pat. No. 5,362,342 discloses a method of bonding tile roof components to a roof substrate utilizing polyurethane foam as the bonding medium. The method includes the step of applying under low pressure a stream of two component foamable liquid polyurethane on a prepared roof substrate. The foamable liquid polyurethane has a density preferably in the range of one and one-half to two pounds per cubic foot and a reactivity period in the range of one and one-half to four minutes. The foamable liquid polyurethane is preferably applied at a rate in the range of two to three pounds per minute. The tile roof component is placed into contact with the foamable liquid polyurethane during the reactivity period of the foamable liquid polyurethane. The bond between the tile roof components and the roof substrate with the polyurethane foam is several times increased over the mortar and mechanical bonds.
It is desirable to provide an energy efficient pitched tile roofing system at a reasonable cost. Thus, it is desirable to have a pitched tile roofing system that provides insulation to reduce energy consumption. It is also desirable in a pitched tile roofing system to minimize the difficulty of precisely aligning and installing the rows of roof tiles to assure the most aesthetically pleasing appearance of the installed roofing system. Furthermore, it is desirable that the method of installation be a simple operation, non-labor intensive, economical and not require excessive installation time. Additionally, the pitched tile roofing system should withstand the long-term effects of temperature and climatic variations experienced by the pitched tile roofing system under normal circumstances.